some are household names such as apple, facebook and twitter. managers at the firms revealed this month they were hit by hackers. someone stole the computer have passwords last october of employees of "the new york times." >> that point we were pretty certain there were some hackers in our network and the fbi said, as did at&t, this had all the hallmarks of hacking by the chinese military. >> reporter: officials at the department of homeland security pulled up some numbers to illustrate what's happening. they say hackers just hit nine u.s. firms in 2009. two years later that figure jumped to 198. analysts at a computer security firm called mandiant blame a unit of the chinese military. the analysts issued this report exposing one of chinese espionage units and they referred to hackers known as the advanced persistent threat. and they say the groups conducting these activities are based primarily in china and they say the chinese government is aware of them. the analysts say a group known as apt1 has targeted nearly 150 victims over seven years,